So far this is the only problem I noticed. All other admin sections seems operational.

I use only fb.module (like button on my content nodes)and followed the installation instructions (README file - 1.Download from http://github.com/facebook/php-sdk. Extract the files, and place them in sites/all/libraries/facebook-php-sdk, 2.Your theme needs the following attribute at the end of the tag: xmlns:fb="http://www.facebook.com/2008/fbml")
So my html now looks like this :
print $language->language " lang=" print $language->language " dir=" print $language->dir ">
print $language->language " lang=" print $language->language " dir=" print $language->dir " xmlns:fb="http://www.facebook.com/2008/fbml">

Like button displays normally on my nodes and seems operational except on frontpage where i display many nodes (teaser views of 1 content type) using ajax. When i click on like button of a node teaser view it "likes" all my nodes...
Also I see no new post on my facebook page unless i comment when I "like".
Should I post the last 2 as separate issues?(sorry I am new in posting issues)

You can re-close after answering. I had this module installed for several days and until just now, when I enabled the jQuery Update and Superfish modules, it was fine without the extension. What would those modules have done to mess up FB?

Then I looked to edit php.ini to reference the curl.so shared object, on the basis that the plethora of curl setup documentation out there is for WAMP and there they mention setting up reference to curl.dll in php.ini So given that I am using Linux I would have thought that it would be necessary to do similar here.

;;;;;;;;;;;;;;;;;;;;;;
; Dynamic Extensions ;
;;;;;;;;;;;;;;;;;;;;;;
; If you wish to have an extension loaded automatically, use the following
; syntax:
;
; extension=modulename.extension
;
; For example, on Windows:
;
; extension=msql.dll
;
; ... or under UNIX:
;
; extension=msql.so
;
; ... or with a path:
;
; extension=/path/to/extension/msql.so
;
; If you only provide the name of the extension, PHP will look for it in its
; default extension directory.
; The following added by Rob Davis 2013-08-30 for drupal for facebook dependency on php curl
; more details here: https://drupal.org/node/964230#comment-7806995
<code>
I add:
<code>
; The following added by Rob Davis 2013-08-30 for drupal for facebook dependency on php curl
; more details here: https://drupal.org/node/964230#comment-7806995
extension=curl.so

> Dave's comment fixed the issue for me - "You should double check your PHP.ini file to ensure that the curl extension is indeed enabled before restarting apache but curl will NOT be working until you restart Apache. "

I opened my php.ini, searched (CTRL+F) for "curl" un-commented the line and re-started Apache. Did not need to uninstall the Facebook modules.